package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.Duration;
import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;

    /**
     * * 根据id查询店铺，并且添加缓存
     *
     * @param id
     * @return
     */
    @Override
    public Object queryById(Long id) {
        //缓存穿透
        //Shop shop = queryWithPassTrough(id);
        //通过工具类来解决缓存穿透
       // Shop shop = cacheClient.queryWithPassTrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //用互斥锁解决缓存击穿
        //Shop shop = queryWithMutex(id);
        //用逻辑过期解决缓存击穿
        //Shop shop = queryWithLogicalExpire(id);
        //使用工具类逻辑过期来解决缓存击穿
        Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //判断shop
        if (shop == null) {
            return Result.fail("店铺不存在");
        }

        return Result.ok(shop);
    }

    //更新缓存
    public Shop queryWithMutex(Long id) {
        //1.从redis查询商铺缓存,对象用hash
        String shopJson = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY + id);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3.存在，直接返回,转换为java对象
            return JSONUtil.toBean(shopJson, Shop.class);

        }
        //判断是否是空值
        if (shopJson != null) {
            //返回错误信息
            return null;
        }
        //4.实现缓存重建
        //4.1.获取互斥锁
        String lockKey = "lock:shop" + id;
        Shop shop = null;
        try {
            boolean flag = tryLock(lockKey);
            //4.2.判断是否成功
            if (!flag) {
                //4.2.1.失败，休眠并重试
                Thread.sleep(50);
                //递归调用
                return queryWithMutex(id);
            }
            //4.4.不存在，根据id查询数据库
            shop = getById(id);
            //5.不存在，返回错误
            if (shop == null) {
                //防止缓存透，将控制写入redis
                stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
                //返回错误信息
                return null;
            }
            //6.存在，写入redis
            stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            //即使发生异常也需要释放锁
            throw new RuntimeException(e);
        } finally {
            //7.释放互斥锁
            unLock(lockKey);
        }
        //8.返回
        return shop;
    }

    //创建线程池
    private static final ExecutorService CACHE_REBUILD_EXECUTOR= Executors.newScheduledThreadPool(10);

    //逻辑过期
    public Shop queryWithLogicalExpire(Long id) {
        String key=CACHE_SHOP_KEY+id;
        //1.从redis查询商铺缓存,对象用hash
        String shopJson = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY + id);
        //2.判断是否存在
        if (StrUtil.isBlank(shopJson)) {
            //3.存在，直接返回null
            return null;

        }
        //4.命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        //获取店铺但是是json格式
        JSONObject data = (JSONObject) redisData.getData();
        //获取shop
         Shop shop = JSONUtil.toBean(data, Shop.class);
         //获取过期时间
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断是否过期
         if (expireTime.isAfter(LocalDateTime.now())) {
             //5.1未过期，直接返回店铺信息
             return shop;
         }
        //5.2.已过期，需要缓存重建
        //6.缓存重建
        //6.1获取互斥锁
         String lockKey = LOCK_SHOP_KEY + id;
            boolean flag = tryLock(lockKey);
        //6.2判断是否获取锁
         if (flag) {
             //6.3成功，开启独立线程实现缓存重建
               CACHE_REBUILD_EXECUTOR.submit(() -> {
                   try {
                       //重建缓存
                       this.saveShop2Redis(id, 20L);
                   } catch (Exception e) {
                       throw new RuntimeException(e);
                   }finally {
                       //释放锁
                       unLock(lockKey);
                   }

               });
         }
        //6.4失败，返回过期商品信息
        return shop;
    }


    /**
     * * 根据id查询店铺，并且添加缓存,缓存穿透
     * @param id
     * @return
     */
    public Object queryWithPassTrough(Long id) {
         //1.从redis查询商铺缓存,对象用hash
        String shopJson = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY + id);
         //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3.存在，直接返回,转换为java对象
            return Result.ok(JSONUtil.toBean(shopJson, Shop.class));
        }
         //判断是否是空值
        if (shopJson !=null) {
            //返回错误信息
            return Result.fail("店铺不存在");
        }
         //4.不存在，根据id查询数据库
        Shop shop = getById(id);
         //5.不存在，返回错误
        if (shop == null) {
            //防止缓存透，将控制写入redis
            stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, "", CACHE_NULL_TTL , TimeUnit.MINUTES);
            //返回错误信息
            return Result.fail("店铺不存在");
        }
           //6.存在，写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
       //7.返回
        return Result.ok(shop);
    }
    //获取互斥锁
    private boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        //使用工具类返回
        return BooleanUtil.isTrue(flag);
    }

    //释放互斥锁
    private void unLock(String key) {
        stringRedisTemplate.delete(key);
    }


    /**
     * * 根据id查询店铺，并且添加缓存，使用逻辑过期
     * @param id
     * @param expireSeconds
     */
    public void saveShop2Redis(Long id,long expireSeconds){
        //1.查询店铺数据
        Shop shop=getById(id);
        //2.封装逻辑过期
        RedisData redisData=new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));
    }

    /**
     * * 更新店铺信息
     *
     * @param shop
     * @return
     */
    @Override
    @Transactional
    public Object update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空");
        }
//        1.更新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //1.判断是否需要根据坐标查询
        if (x == null || y == null) {
            //不需要坐标查询，按数据库查询
            // 根据类型分页查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        //2.计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;
        //3.查询redis，按照距离排序，分页。结果：shopId，distance
        String key=SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo().search(
                key,
                GeoReference.fromCoordinate(x, y),
                new Distance(5000),
                RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
        );
        //4.解析出id
        if (results == null) {

            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        //4.1.截取from到end的部分
        List<Long> ids=new ArrayList<>(list.size());
        Map<String,Distance> distanceMap=new HashMap<>(list.size());
        list.stream().skip(from).forEach(
                result -> {
                    //4.2获取店铺id
                    String shopIdStr = result.getContent().getName();
                    ids.add(Long.valueOf(shopIdStr));
                    //4.3.获取距离
                    Distance distance = result.getDistance();
                    distanceMap.put(shopIdStr,distance);
                });
        if (ids == null || ids.size() == 0) {
            return Result.ok(Collections.emptyList());
        }
        //5.根据id查询Shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id,"+idStr+")").list();
        //6.包装Shop，返回
        for (Shop shop : shops) {
                shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        //6.返回
        return Result.ok(shops);
    }
}
